This supplemental grant proposes to add questions to extend the aims of the parent project by collecting additional data related to COVID-19 including financial hardships, social/interpersonal problems, stress, mental health, and substance use changes. Data will also be collected on whether participants are essential workers, were exposed to COVID-19, or have been diagnosed with COVID-19. Parent grant Aim 1: Effect of RML on substance use/misuse, mental health, & psychosocial function Aim 1 extended: Effect of COVID-19 pandemic and RML on substance use/misuse, mental health & psychosocial function. We will test the hypothesis that access to RML increases the likelihood that the stress and disruption associated with COVID-19 will lead to increased marijuana use and abuse. Relatedly, we will test the extent to which increased marijuana use, related to RML and stress/disruptions from COVID-19, is accompanied by increases in other substance use, mental health disorders, or psychosocial dysfunction. Parent grant Aim 2: Individual differences in the effect of RML Aim 2 extended: Examine individual differences in the effect of COVID-19 pandemic and RML. Examine individual differences in the effects of COVID-19 and legalization by leveraging parallel multi-wave longitudinal twin studies in CO and MN, which both began collecting substance use, psychopathology, and psychosocial function during the twins' adolescence. This supplemental assessment will allow us to: a) identify how COVID-19 differentially impacts individuals depending on legalization and prior exposure to marijuana; b) examine how individuals differ in their vulnerability and resilience to the effects COVID-19, in the context of legalization, based on their individual level of risk (e.g., prior diagnosis of anxiety or depression); and c) examine if there are differential associations between COVID-19 and substance use/dependence, mental health, and psychosocial problems depending on legalization status and gender.